1. Field of the Invention
The present invention relates to a machine tool with an automatic tool change function, which is capable of making engagement between a key of a tool spindle and a key-way of a tool or a tool holder without stopping rotation of the spindle.
2. Description of the Prior Art
Conventionally, in order to allow for engagement between a key of a tool spindle and a key-way of a tool, the spindle is stopped at a predetermined angular position, which results in a longer time period for tool change operation.
Accordingly, it is extremely effective to perform a tool change operation without stopping the spindle at the predetermined angular position for shortening the required time for tool changing operation. On the other hand, the tool is usually provided with two key-ways at diametrically opposite positions, and thus it is necessary to engage the key with one predetermined key-way of first and second key-ways for maintaining a constant taper engagement between the spindle and the tool.